Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus[Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2013	$ 387,623	$ 46,249	$ 107,596	$ 333,970	$ (95,202)	$ (4,990)
Net income	26,560			26,560
Other comprehensive income (loss)	2,481					2,481
Cash dividends declared	(12,512)			(12,512)
Stock-based compensation expense, net	889		(494)		1,383
Exercise of stock options	553		(272)		825
Purchase of treasury shares	(8,363)				(8,363)
Ending balance at Jun. 30, 2014	397,231	46,249	106,830	348,018	(101,357)	(2,509)
Beginning Balance at Dec. 31, 2014	390,853	46,249	107,370	362,211	(120,818)	(4,159)
Net income	29,975			29,975
Other comprehensive income (loss)	(733)					(733)
Cash dividends declared	(12,807)			(12,807)
Stock-based compensation expense, net	1,060		(408)		1,468
Exercise of stock options	996		(306)		1,302
Exercise of warrants	1,896		(765)		2,661
Ending balance at Jun. 30, 2015	$ 411,240	$ 46,249	$ 105,891	$ 379,379	$ (115,387)	$ (4,892)